How organisms respond to light and how photosensory receptors mediate light responses are some of the most basic questions in biology that affect human health. Cryptochromes (CRY) are blue/UV-A light receptors found in bacteria, plants, and animals including human, but the molecular mechanisms of CRYs remain not well understood. My laboratory uses Arabidopsis as the model system to study signaling mechanisms underlying CRY1 and CRY2 regulation of plant development. We recently identified, for the first time, blue light-dependent CRY-interacting proteins in plants. We propose to continue study CRY1 and CRY2 signaling mechanisms with three specific aims. First, we propose to investigate how CRY-interacting proteins regulate transcription, mRNA export, and protein stability. Second, we plan to investigate CRY regulation of cell-type- specific gene expression changes. Third, we propose to identify and characterize genes affecting blue light-induced CRY2 degradation and blue light- suppressed CIB1 degradation. PUBLIC HEALTH RELEVANCE: Cryptochromes (CRY) are blue/UV-A light receptors regulating plant development and human health. We propose to study CRY-interacting proteins and how they mediate CRY regulation of gene expression in response to light.